This invention relates to a fluid machinery driven equipment that performs energy exchange between a rotary fluid machinery and fluid such as gas or liquid, and more particularly, to a driven equipment such as a rotary pump involving piston rotation in which an outer edge of the piston slides along an inner elliptical surface of the rotary pump to perform intake and exhaust actions.
With continuing progress in science and technology, various types of fluid machinery driven equipment have been developed with improved performances. This invention is directed to a displacement type rotary driven equipment, such as a rotary pump, a rotary compressor, a gear pump, a scroll pump and the like.
Rotary driven equipment is widely used in the industry. However, rotary driven equipment of today is still inefficient in energy exchange and is complex in configuration. Further, because of the structural complexity, the physical size and cost of such rotary driven equipment is not small enough to be widely used in various applications.
Therefore, it is an object of the present invention to overcome the aforementioned problems and to provide a fluid machinery driven equipment having a simple structure and a high efficiency with a small size and low cost.
In the present invention, the driven equipment for fluid machinery which is driven by an external power includes a tubular casing having an inner surface which is substantially elliptic in shape, front and rear covers for covering the tubular casing through fastening means, a rotary shaft provided in the tubular casing and is supported by the front and rear covers where at least one end of the rotary shaft being projected from the cover to be connected to the external power, and a rotor provided in the tubular casing and connected to the rotary shaft.
The rotor is formed of a first arm extended from a center of the rotor to opposite directions, a piston rotatably connected to each end of the first arm through a piston pin and forming substantially a xe2x80x9cTxe2x80x9d shape with the first arm where the piston having an outwardly curved surface, and each end of the piston has an inwardly bent portion, a second arm extended from the center of the rotor to opposite directions in perpendicular to the first arm, a rotary plate provided at each end of the second arm and forming substantially a xe2x80x9cTxe2x80x9d shape where the rotary plate having an outwardly curved surface, and an inner surface at each end of the rotary plate is slidably contact with an outward surface of the inwardly bent portion of the piston, piston seals elastically formed on the piston at around both edges thereof for air tightly contacting the inner surface of the tubular casing, and a spring provided between the second arm and the piston for reducing frictional forces between the piston seals and the inner surface of the tubular casing.
The driven equipment further includes first openings provided on the tubular casing at two positions which are symmetrical with one another relative to the rotary shaft, and second openings provided on the covers at two positions which are symmetrical with one another relative to the rotary shaft and about 90 degrees apart from the first openings relative to the rotary shaft. When the first openings function as intake openings, the second openings function as exhaust openings, and vice versa.
In the driven equipment of the present invention, four spaces are created by the inner surface of the tubular casing and the rotor, two of which are spaces formed by the pistons at both ends of the first arm and the inner surface, and two other spaces are formed by the rotary plates at both ends of the second arm and the inner surface. The sizes of the four spaces change by rotation of the rotor, thereby performing an intake and exhaust actions for fluid.
In the driven equipment of the present invention, the elliptical shape of the inner surface of the tubular casing is determined by the following steps of:
(1) drafting a circuit K with a radius R1 with respect to a center O, where the center O corresponds to the center of the rotation shaft,
(2) drafting a straight line AC which is tangential to the circuit K at a center E of the line AC,
(3) extending a line EO and drafting an arc ABC with respect to a center J on the line EO with a radius R2, where a point B is a cross point of the line EO and the art ABC,
(4) moving the point A of the straight line AC along the arc ABC to the point B in a manner that the center E moves along the circle K, and drafting the trace of the point C of the line AC to form a curve ABCD, and
(5) defining an outer curve which is outwardly apart from the curve ABCD by a distance X,
wherein the outer curve is the inner surface of the tubular casing, and the circle K is a trace of rotation of the piston pin and the curve ABCD is a reference casing curve.
In the further aspect of the present invention, the spring for reducing the friction between the piston seals and the inner surface of the tubular casing is obviated to promote energy conversion efficiency. Both of the intake and exhaust openings are provided on the tubular casing which are about 90 degrees apart from one another with respect to the rotation shaft. Seals are additionally provided between the rotary plates and the pistons.